Difficulty creating mold for fiberglass mold fabrication

I have a part I'm trying to design for a personal project. This was my first attempt at using surfaces and thicken to create a complex, thin part. I've tried following tutorials for two part mold design but I've had no luck implementing the techniques on my part. I'm starting to think that the geometry resulting from the surfaces/thicken may be the issue. My end goal is to create a simple 2 piece fiberglass mold. I've attached the part - would anyone be willing to take a look and lend a hand?

SolidworksPlastics And Mold Design